Method and system for traffic control for providing quality of service in a network

ABSTRACT

A method and system for providing QoS in a network using traffic management including traffic stream admission and traffic control, is provided. The traffic stream admission and control is achieved using parameterized QoS within a network. Such parameterized QoS enhances QoS service in the UPnP QoS architecture.

RELATED APPLICATION

This application claims priority from U.S. Provisional PatentApplication Serial No. Ser. No. 60/780,399 filed on Mar. 7, 2006,incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to providing Quality of Service (QoS) in anetwork.

BACKGROUND OF THE INVENTION

With the proliferation of networks and connectivity, the need for accessto various networks is increasing. Applications that access a network,such as a home network, can be broadly divided into two categories:real-time and non-real-time. Real-time access to the network includesaccess to data streams such as video or audio, etc., from the network.Non-real-time access to the network includes access to data streams suchas e-mail, web pages, File-Transfer Protocol (FTP) downloads, etc., fromthe network. Real-time data-streams have required bandwidth constraints,while non-real-time data-streams are provided on best efforts trafficwithout bandwidth constraints.

Quality of Service (QoS) refers to the ability of a network to providebetter service for selected network traffic over various technologies.QoS can be quantized by a set of parameters such as bandwidth, delay,delay jitters, priority, etc. QoS provides priority including dedicatedbandwidth, controlled jitter and latency for real-time traffic, andimproved loss characteristics.

In the context of home networking, QoS can be achieved using twodifferent types of design principles: prioritized QoS and parameterizedQoS. Prioritized QoS uses priority tagging to place different types oftraffic in different queues. Certain applications (e.g., voice) receivepriority treatment, but not a reserved or guaranteed bandwidth.Parameterized QoS provides a certain level of guarantee on bandwidth,delay and jitter.

The Universal Plug and Play (UPnP) QoS 2.0 architecture used in manynetworks provides priority based QoS, but does not provide any mechanismfor parameterized QoS service. Such parameterized QoS service isrequired for efficient bandwidth and admission control within a network,such as a home network. Further, UPnP QoS 2.0 and Digital Living NetworkAlliance (DLNA) 1.5 do not provide solutions for establishing QoS for asession and for change of QoS during the session. There is, therefore, aneed for method and system for parameterized QoS within a network.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a method and system for providing QoS ina network using traffic management including traffic stream admissionand traffic control. In one embodiment, such traffic stream admissionand control is achieved using parameterized QoS within a network. In oneimplementation, such parameterized QoS enhances QoS service in the UPnPQoS architecture (e.g., UPnP 2.0/3.0 within a home network).

The present invention enhances existing UPnP QOS architectures byproviding a mechanism to control network bandwidth and reduce trafficdelay/jitters in the network. This is achieved by providing an admissioncontrol mechanism that makes admission decisions based on parameterizedinformation gathered about the network traffic. Such traffic informationincludes receiving feedback from admission control module, UPnP QoSDevices and UPnP end devices and source devices in a network. Further,based on information gathered from the network traffic, existing trafficstreams in the network are also controlled by upgrading and downgradingpriorities of existing traffic streams.

These and other features, aspects and advantages of the presentinvention will become understood with reference to the followingdescription, appended claims and accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a functional architecture of an example network, such as ahome network, embodying aspects of the present invention.

FIG. 2 shows example architecture for parameterized QoS within anetwork, according to an embodiment of the present invention.

FIG. 3 shows a flowchart of a process for parameterized QoS in anetwork, according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a method and system for providing QoS ina network using traffic management including traffic stream admissionand traffic control. This is achieved using parameterized QoS in anetwork. In one example, such parameterized QoS is used to controlnetwork bandwidth and reduce traffic delay and jitter for enhancingexisting UPnP QOS architectures.

An admission control entity makes source admission decisions based onthe available bandwidth in the network and based on the informationgathered from the home network traffic. The bandwidth information isrelated to traffic information feedback from UPnP QoS Devices, UPnP enddevices and source devices, in a network. Further, based on theinformation gathered from the network traffic, existing traffic streamsin the network are also controlled by upgrading and downgradingpriorities of existing traffic streams.

FIG. 1 shows a functional architecture of an example network 10, such asa home network, embodying aspects of the present invention. The network10 comprises devices 20 which may include content, consumer electronic(CE) devices 30 which may include content, a PC 21 and an optionalinterface 40 that connects the network 10 to an external network 50(e.g., another local network, the Internet, etc.). The external networkcan be connected to one or more servers 51. The devices 20, 21 and 30,implement the Hyper Text Transfer Protocol (HTTP) protocol which usesUPnP for communication in the network 10. The UPnP specification isbased on Transmission Control Protocol/Internet Protocol (TCP/IP) andInternet protocols that let devices communicate with each other.

The Internet Protocol (IP) data packet traffic within the home network10 comprises primarily TCP and User Datagram Protocol (UDP) traffic. Thedevices within the home network 10 use both real and non-real-timetraffic. The real-time applications such as audio/video streamingusually rely on HTTP and Real-time Transport Protocol (RTP). HTTP andRTP use TCP and UDP, respectively, as their base transport protocols.The non-real-time applications such as FTP also use TCP/UDP as atransport protocol.

The present invention enables enhanced QoS within the network 10 byproviding said admission control mechanism that controls the consumptionof bandwidth of TCP and UDP traffic within the network 10 using anextended UPnP QoS architecture according to the present invention.According to the extended QoS architecture, a data sender (e.g., adevice 30) receives feedback from a UPnP QoSManager service (i.e., aQoSManager module) which is responsible for aggregating feedbacks fromother QoS entities such as senders and receivers. The data sender thencontrols the rate of data transmission into the network 10 from thatsender.

In this example, the admission control mechanism is implemented in anintermediary module such as an admission controller 35 which can be partof a QoSManager (e.g., QoSManager 106 in FIG. 2), or a separate entitythat the QoSManager communicates with before admitting any trafficstream into the network. Based on information gathered about the networktraffic, the intermediary module also controls existing traffic streamsin the network such as by upgrading and downgrading priorities ofexisting traffic streams.

In one example, the present invention provides improved TCP Flow Controland RTP Flow Control. The admission controller 35 utilizes feedback fromTCP flow control, to control (e.g., restrict) TCP bandwidth, andutilizes the RTP report packets to control (e.g., restrict) RTP-basedstreaming traffic. The feedback from the UPnP QoSManager service and thefeedback from the TCP flow control are gathered by the QoSManager toprovide effective QoS in the network 10.

TCP Flow Control

Every TCP connection between a sender (e.g., a source device 30) and areceiver (e.g., a sink device 20), maintains a flow-control window(fwnd) and a congestion control window (cwnd). The sender infers cwndfrom network loss behavior, and the sender receives cwnd from thereceiver as an advertisement. The sender uses the lesser of fwnd andcwnd (i.e., min (fwnd, cwnd)) as the effective window to calculate thebandwidth of the TCP connection. The rate of data transfer (RDT) is theproduct of round trip time (RTT), and minimum of fwnd and cwnd, as:RDT=RTT*min (fwnd, cwnd).

Using the admission control mechanism to control the rate of datatransfer at the sender, bandwidth within the network is controlled.HTTP-based streaming uses TCP flow control (congestion window: cwnd,fwnd, etc.), to limit bandwidth from the sender in the home networkbased on the available bandwidth in the network and the requested QoS.Flow control is enforced by the UPnP QoSPolicy Holder and the QoSManagerservice at the sender. This extends the appropriate functionallyrequired, to the UPnP entities QosDevice, QoSPolicyHolder andQoSManager, in order to enforce TCP flow and admission control.

RTP Flow Control

The admission controller 35 uses a sender report (SR) and a receiverreport (RR) for Real-Time Transport Control Protocol (RTCP) packets ofinformation, to calculate bandwidth information and delayinformationwithin the network, and makes admission control policy decisionstherefrom. RTCP parameters provided by the admission controller 35notify each sender to control its rate of transmission.

Extending UPnP QoS Architecture

In this example, the conventional logical architecture of UPnP QoS 2.0is extended with additional features provided in the UPnP QosDevice andQosManager services. FIG. 2 shows architecture of an example system 100for Parameterized QoS within the UPnP network such as the network 10 inFIG. 1, according to the present invention. A sender (source) 30 and areceiver (sink) 20 implement QosDevice services 102, 104, respectively,or at least part of those services.

The QoS Device services 102, 104, provide feedback to a UPnP QosManager106 (e.g., implemented in a UPnP capable router, or access point), abouttraffic stream communication between the sender 30 and the receiver 20in the network. The sender 30 further includes a UPnP AV 103 whichessentially provides an audio/video streaming function (e.g., selectionof a media content from a UPnP storage device (digital media server)),between a media storage device and a media renderer device (e.g., TV,digital media player, etc.) in the UPnP network. The UPnP AV 103 alsoprovides control functionality to control audio/video media such asstart/stop/play, select, etc. The receiver 20 also includes a UPnP AV105.

In the conventional QoS 2.0 architecture, the only way to obtaininformation about traffic from a QosDevice is to use a GetQosStateaction to obtain information about the currently active traffic streamson the device using TrafficDescriptor structures. However, theconventional QoS 2.0 TrafficDescriptor structure is inadequate inproviding bandwidth, delay and delay jitter, etc., information.

An extended UPnP QoS architecture according to the present inventionincludes a Traffic specification (Tspec) structure that includes QoSparameters. In one example, the Tspec structure includes a set of QoSparameters that define the characteristics of a traffic stream. TheTspec specifies in detail the QoS requirements for a traffic stream. TheQoS parameters include, but are not limited to, bandwidth information,delay information, jitter information, etc. When the UPnP control pointrequests QoS for a traffic stream, that stream is described in the Tspecthat the control point submits. Such information is then used by thevarious UPnP QoS entities (QoSManager, QoSPolicy Holder and QoSDevice)to determine the proper handling for the stream. As such, the Tspecstructure should always be submitted with as much information as isknown at the time.

When a UPnP control point wishes to admit a QoS stream into the network,the UPnP control point creates a Tspec structure for that specifictraffic stream and invokes a UPnP action to the UPnP QoSManager to admitthat stream into the network.

For example, contention-based medium access is susceptible to severeperformance degradation when overloaded. In overload conditions, thecontention windows become large, and more and more time is spent inbackoff delays rather than sending data. Admission control according tothe present invention regulates the amount of data contending for themedium. Such admission control is negotiated by the use of a Tspec,which is the primary mechanism for communication of QoS parameters to aUPnP QoSManagementEntity implementing traffic admission/controlaccording to an embodiment of the present invention. TheQoSManagementEntity can be implemented in the QosManager or in aseparate admission controller, for traffic admission and control ofexisting traffic streams.

As shown in FIG. 2, the QoSDevice 102 of the sender 30 provides feedback(updates) of sender QoS parameters to the QoSManager 106. Similarly, theQoSDevice 104 of the receiver 20 provides feedback (updates) of receiverQoS parameters to the QoSManager 106. An UpdateQosState action isprovided for use by the QoSDevice 102 of the sender 30, and theQoSDevice 104 of the receiver 20, to provide such feedbacks to theQosManager 106, indicating a global view of QoS parameters in thenetwork. The UpdateQosState action name is provided as an example, andcan be another name. The QoS parameters include bandwidth information,delay information, jitter information, etc. The UpdateQosState action isimplemented by the UPnP QoSManager for invocation on a QoS Device,wherein the QoSDevice provides the invocation interface. Global QoSstatus involves obtaining traffic information from all of the receivers,senders and intermediary devices, to make traffic management decisions.This also includes obtaining feedback from the TCP flow control, theRTCP XR reports and layer 2 QoS data from intermediary devices. AQosManager can also obtain traffic information from a QosDevice by UPnPeventing. Whenever there is a change in traffic information in aQosDevice device, that particular device sends information events aboutthe changes to the QosManager. The QosManager needs to subscribe toreceive change of traffic information event state variables. The statevariable includes traffic information such as bandwidth, delay, etc.

Utilizing said feedbacks, the QoSManager 106 controls the QoS parametersby invoking appropriate actions. For example, the QosManager 106 invokesan UpdateTrafficQoS action to instruct the sender 30 to control thetraffic the sender 30 inserts into the network by using flow controlprocedures. The UpdateTrafficQoS action is invoked by the UPnPQoSManagementEntity implemented in the UPnP QoSManager for instructingthe sender to reduce the amount of traffic inserted by the sender by anamount specified by the UpdateTrafficQoS action.

New Roles for UPnP QosManager Service

When a UPnP control point desires to admit a QoS stream into thenetwork, the UPnP control point creates a Tspec for that specifictraffic stream and invokes a UPnP action to the UPnP QoSManager tocontrol admission of that traffic stream into the network.

The role of a conventional QosManager service is extended according tothe present invention, to incorporate additional features in the UPnPQosManager 106 for making well-informed decisions about controllingadmission of such traffic (e.g., streaming, etc.) into the network, andabout bandwidth management by controlling the rate of existing streamsin the network.

In one example, such extensions for the UPnP QosManager 106 according tothe present invention include:

a) RTCP Packet Monitoring and Controlling the RTP Source

-   -   The UPnP QosManager 106 monitors the RTP Control Protocol        Extended Reports (RTCP XR) which provide traffic information in        the UPnP network. Using the RTCP XR reports, the QosManager 106        calculates the average payload data rate and the average packet        rate over an interval. The QoSManager 106 further calculates the        throughput available to the receiver 20. The UPnP QosManager 106        provides appropriate feedback (e.g., information about available        throughput, packets received or lost, etc., since the last        report) to the sender(s) 30 and receiver(s) 20. The sender 30        modifies its transmissions based on the feedback from the        QosManager 106 (e.g., sender 30 increases its transmission rate        to the receiver 20).    -   The QosManager 106 need only receive the RTCP XR packets and not        the corresponding RTP data packets, to evaluate the performance        of the network for multicast distribution of data. The        QosManager 106 can use inter-arrival jitter information to        obtain a short-term measure of network congestion. A jitter        measure may indicate congestion before it leads to packet loss.        The QosManager 106 determines new traffic admission in the        network based on the RTCP XR traffic parameters.

b) Monitoring and Controlling the TCP Senders by the QosManager

-   -   The QosManager 106 monitors initiators of TCP traffic in the        UPnP network. For example, the QosManager 106 monitors the TCP        flow control/bandwidth parameters from the sender(s) 30 and        generates an aggregated TCP throughput in the entire network.        Once the QosManager 106 has overall information about the        network bandwidth, it can apply admission and bandwidth control        policy by upgrading/downgrading existing traffic, based on the        available bandwidth.

Aggregation of QoS Related Information for Admission Control

According to a further implementation of the present invention, for moreinformed admission decisions for future traffic, an overall view ofbandwidth utilization in the network is obtained. In one example, thisis achieved by aggregating the layer 2 QoS related information(bandwidth, congestion, etc.) received from the QoS Devices 102, 103 inthe network, with layer 3 (and higher) QoS information received from theRTCP XR reports along with the TCP flow control feedbacks. This providesparameterized QoS in the network to provide efficient management ofnetwork bandwidth, and reduce congestion in the network by using anefficient admission control mechanism.

Further, aggregation of layer 2 QoS information with layer 3 (andhigher) QoS feedbacks, allows informed admission and bandwidth controlin the network. This enhances UPnP QoS 2.0/3.0 without changing thebasic UPnP QoS architecture.

In one example, the UPnP QoSManager 106 as an intermediary moduleperforms the aggregation. In another example, other intermediary modulesthat admits and/or controls traffic (e.g., QoS device) in the networkcan also perform the aggregation. The intermediary module can reside inthe QosManager itself or can be a separate entity.

The present invention further provides a mechanism to restrict TCP/RTPbandwidth in the network by providing feedback information to the sender30, and by monitoring the TCP/RTP traffic in the network. As such, thepresent invention allows real-time control, establishment and change ofQoS for sessions between the senders 30 and receivers 20, by controllingthe throughput of the sender(s) 30 in the network.

FIG. 3 shows a control flow 200 for traffic admission control in anetwork, including multiple QoSDevices 202A-C and a QosManager 204,according to an embodiment of the present invention, including thefollowing steps (also shown in FIG. 3):

-   -   Step 1: Each of one or more QoSDevices gather QoS related        information (e.g., traffic, bandwidth, delay jitters, etc.) from        traffic streams into and out of that QoS device. FIG. 3 shows        QoSDevice 202A gathering traffic information, and preferably        other QoSDevices perform the same step.

The QoSManager retrieves/receives QoS related information (layer 2, 3 orhigher) for various traffic streams from the QoSDevices by using one ormore of the following steps:

-   -   Step 2 a: The QoSManager can invoke a GetQosState action to        retrieve such QoS related information from one or more        QosDevices (e.g., QoSDevice 202A).    -   Step 2 b: The QoSManager can also retrieve such QoS related        information from one or more QoSDevices (e.g., QoSDevice 202C)        by using a UPnP eventing mechanism. The QoSManager subscribes        for QoS state changes of source and the sink QoSDevices, and        whenever there is a change in a QoS state of a QoSDevice, that        QoSDevice sends updates to the QoSManager as RTCP XR reports.    -   Step 2 c: The QoSManager can also retrieve such traffic        information from one or more QoSDevices (e.g., QoSDevice 202B),        using the RTCP XR reports from the QoSDevices for RTP streaming.    -   Step 3: Using the retrieved/received traffic information, the        QoSManager calculates the aggregate bandwidth used by various        traffic streams. Using the bandwidth calculation, the QoSManager        decides whether to downgrade or upgrade traffic parameters for a        stream output from a QoSDevice (e.g., QoSDevice 202B) based on        traffic importance of the streams. The downgrade or upgrade is        performed by invoking a UPnP action, or by using out of band        (not UPnP) mechanisms, on one or more QoSDevices as necessary.        An upgrade provides more bandwidth for a stream (e.g., the        source QoSDevice reduces the stream rate), and a downgrade        reduces the bandwidth available for a stream (e.g., the source        QoSDevice increases the stream rate). An upgrade decision for a        stream can be made when there is available bandwidth in the        network. A downgrade decision for a stream can be made when        bandwidth must be made available for upgrade of another stream        (e.g., a delay/jitter sensitive stream such as a real-time        stream), or for admission of a new stream.    -   Step 4: A source QoSDevice (e.g., UPnP control point) submits a        request to admit a traffic stream to the network.    -   Step 5: When a QosManager receives a request from a source        QoSDevice to admit a new stream to the network, the QosManager        compares the total network bandwidth against a calculated        aggregate bandwidth used by all of the traffic streams in the        network, to determine whether to admit this new traffic stream.        In one example, the traffic stream is admitted if there remains        an available portion of the total bandwidth in the network.

Though in the example shown in FIG. 3 the QoSManager performs admissioncontrol, such admission control can be implemented in a separateadmission entity (e.g., admission controller 35 in FIG. 1) in thenetwork, such that the QosManager contacts the admission entity toobtain a decision on admission of a traffic stream.

Other examples of upgrade/downgrade/admission decision making (based ontotal network bandwidth, calculated aggregate bandwidth used by all ofthe traffic streams in the network, etc.) can be implemented to controlnetwork traffic and manage bandwidth requirements for QoS, according tothe present invention. Further, there can be more than one intermediarymodule (e.g., admission controller) in the network for handling trafficadmission and management.

As is known to those skilled in the art, the aforementioned examplearchitectures described above, according to the present invention, canbe implemented in many ways, such as program instructions for executionby a processor, as logic circuits, as an application specific integratedcircuit, as firmware, etc.

The present invention has been described in considerable detail withreference to certain preferred versions thereof; however, other versionsare possible. Therefore, the spirit and scope of the appended claimsshould not be limited to the description of the preferred versionscontained herein.

1. A method for providing Quality of Service (QoS) within a networkincluding devices, comprising the steps of: obtaining parameterizedtraffic information from the network; and performing traffic managementby traffic stream admission and traffic control in the network, based onthe traffic information.
 2. The method of claim 1 wherein performingtraffic management includes traffic stream admission and traffic controlfor reducing traffic delay and jitters based on the traffic information.3. The method of claim 1 wherein performing traffic management includesproviding a UPnP management module including a UPnP QoSManagerimplementing traffic management in the network based on the trafficinformation.
 4. The method of claim 3 further including the step of theUPnP QoSManager controlling consumption of bandwidth of TCP and UDPtraffic within the network at layer 3 and higher.
 5. The method of claim3 further including the step of the UPnP QoSManager controllingconsumption of bandwidth of TCP and UDP traffic within the network atboth layer 2 QoS information in addition to layer 3 and higher.
 6. Themethod of claim 3 wherein performing admission control further includes:the UPnP QoSManager determining an available network throughput based onthe traffic information; providing network throughput information fromthe UPnP QosManager to a sender device in the network; and based on thenetwork throughput information, the sender device controlling the rateof data transmission from the sender into the network.
 7. The method ofclaim 6 further including the steps of: aggregating said trafficinformation including TCP flow control; the UPnP QoSManager determiningavailable network throughput based on the aggregated trafficinformation; and controlling TCP bandwidth used by the sender based onthe network throughput information.
 8. The method of claim 7 wherein:said traffic information includes RTP report packets from devices in thenetwork; and controlling TCP bandwidth includes controlling RTP-basedstreaming traffic based on the network throughput information.
 9. Themethod of claim 6 further including the step of: a sender and receiverin the network each implementing a QosDevice service, wherein theQosDevice services provide to the QosManager information about trafficstream communication between the sender and the receiver.
 10. The methodof claim 6 further including the step of providing a Trafficspecification (Tspec) structure that includes parameterized QoSinformation.
 11. The method of claim 10 further including the step of: aUPnP control point providing a Traffic specification (Tspec) structurethat includes QoS parameters for a traffic stream, to request admissionof the traffic stream into the network from the QoSManager.
 12. Themethod of claim 6 further including the step of: providing an action fora QosManager to invoke a QosDevice to provide feedback for trafficinformation, including a global status of QoS parameters in the network,to the QosManager.
 13. The method of claim 6 further including the stepof: the QosManager receiving traffic information from a QosDevice byUPnP eventing.
 14. The method of claim 12 further including the stepsof: providing an UpdateTrafficQoS action for traffic control; and theQoSManager invoking an UpdateTrafficQoS action based on the trafficinformation to instruct the sender to control the flow of traffic thesender inserts into the network.
 15. The method of claim 1 whereinperforming traffic management includes: providing a UPnP intermediarymodule implementing traffic management in the network based on thetraffic information and the QosManager interacting with the intermediarymodule to make traffic management decisions.
 16. The method of claim 1wherein performing traffic management includes providing a UPnPQoSManager implementing traffic management in the network based on thetraffic information.
 17. A system for parameterized QoS within a networkof one or more senders and one or more receivers, comprising: means forobtaining traffic information within the network; and a controller thatis configured for managing traffic inserted by a sender into the networkusing the traffic information, the controller including a UPnPQoSManager configured for monitoring RTCP XR reports from devices in thenetwork, and providing traffic feedback to the sender based on thereports, to manage traffic in the network, wherein the traffic feedbackenables the sender to control the rate of data transmission from thesender into the network.
 18. The system of claim 17 wherein theQoSManager is further configured to provide said traffic feedback bycalculating the average payload data rate and the average packet rateover an interval using RTCP XR reports, calculating the throughputavailable, and providing the calculation results as traffic feedback.19. The system of claim 18 wherein the sender is configured to controlits rate of data transmission into the network by modifying itstransmissions based on the traffic feedback from the QosManager and RTCPXR reports.
 20. The system of claim 19 wherein the QoSManager is furtherconfigured to receive the RTCP packets without requiring thecorresponding RTP data packets, to determine network performance inmulticast distribution, for generating said traffic feedback.
 21. Thesystem of claim 20 wherein the QoSManager is further configured toutilize inter-arrival jitter information to obtain a short-term measureof network congestion for generating said traffic feedback.
 22. Thesystem of claim 21 wherein a jitter measure indicates congestion beforecausing packet loss.
 23. The system of claim 22 wherein the QoSManageris further configured to determine new traffic admission in the networkbased on the RTCP traffic parameters.
 24. The system of claim 17 furtherincluding: a UPnP control point that is configured to provide a Trafficspecification (Tspec) structure that includes QoS parameters for atraffic stream, to request admission of the traffic stream into thenetwork from the QoSManager.
 25. The system of claim 17 wherein theQoSManager is further configured to monitor initiators of TCP trafficand monitor the TCP flow control/bandwidth parameters from the sender,to determine an aggregated TCP throughput in the network for generatingsaid traffic feedback.
 26. The system of claim 25 wherein the QoSManageris further configured to apply admission and bandwidth control policybased on the available bandwidth in the network, for generating saidtraffic feedback.
 27. The system of claim 17 wherein the QosManager isfurther configured to perform traffic management by utilizing feedbacksfrom both TCP based flow control and RTCP feedbacks.
 28. The system ofclaim 17 wherein the QosManager is further configured to make trafficmanagement decisions based on using layer 2 QoS information, and layer 3and higher feedback including TCP flow control and RTCP feedbacks.